A fifth consortium of Wates and architect Bisset Adams withdrew after expressing uncertainty over the exact scope of the project.

As well as the main offices, the scheme aims to include "ancillary" features, such as residential accommodation, and community facilities such as cafes and crèches.

Nick Dockree, project manager at Urban Catalyst, said the project was a unique opportunity to build a civic town hall of the type popularised in the 19th century.

He said: "The design will aim to animate the area. We want innovation to be at the heart of the project, with sustainable development and aesthetically pleasing design.

"It's a one-off opportunity to create a real town hall of the Victorian era. There aren't many around at the moment."

Agents CB Richard Ellis and Dearle & Henderson have been appointed property advisers to the council on design-and-build contracts.

All four teams have been invited to submit detailed proposals, and a decision is to be made by the end of the year. The new headquarters, which has not yet been definitively costed, is expected to be complete in two to three years.